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Enrichment gives exceptions for non 2 isotopes

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Following discussion in the issues the functionality to enrich mixtures
of more then 2 nuclides is block by an exception. The algorithim should
still support larger mixtures.
This commit is contained in:
Mikolaj Adam Kowalski 2020-02-14 16:12:44 +00:00
parent a3ac3fb478
commit 1e432863b1
1 changed files with 48 additions and 32 deletions
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80
openmc/element.py
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@ -35,7 +35,8 @@ class Element(str):
return self
def expand(self, percent, percent_type, enrichment=None,
enrichment_target=None, cross_sections=None):
enrichment_target=None, enrichment_type='ao',
cross_sections=None):
"""Expand natural element into its naturally-occurring isotopes.
An optional cross_sections argument or the OPENMC_CROSS_SECTIONS
@ -52,12 +53,15 @@ class Element(str):
percent_type : {'ao', 'wo'}
'ao' for atom percent and 'wo' for weight percent
enrichment : float, optional
Enrichment of an enrichment_taget nuclide in weight percent. If
enrichment_taget is not supplied then it is enrichment for U235 in
Enrichment of an enrichment_taget nuclide in percent (ao or wo).
If enrichment_taget is not supplied then it is enrichment for U235 in
weight percent. For example, input 4.95 for 4.95 weight percent
enriched U. Default is None (natural composition).
enrichment_target: str, optional
Single nuclide name to enrich from a natural composition e.g. O16
enrichment_type: {'ao', 'wo'}, optional
'ao' for enrichment as atom percent and 'wo' for weight percent.
Default is 'ao'
cross_sections : str, optional
Location of cross_sections.xml file. Default is None.
@ -78,11 +82,12 @@ class Element(str):
library and element is not O, W or Ta
ValueError
Enrichment of isotope not present in natural composition of
the element is requested
Enrichment of isotope which is not present in natural composition
of the element is requested
ValueError
Enrichment is requested of the element composed of single isotope
Enrichment is requested of the element composed of more or less
then 2 isotopes.
Notes
-----
@ -208,6 +213,13 @@ class Element(str):
# Interpret required enrichment as weight %
elif enrichment is not None and enrichment_target is not None:
# Check if is a single isotope mixture
if len(abundances) != 2:
msg = 'Element {0} does not consist of 2 isotopes. Thus it '\
'cannot be enriched with in-build procedure. Please '\
'enter isotopic abundances manually. '.format(self)
raise ValueError(msg)
# Check if the target nuclide is present in the mixture
if enrichment_target not in abundances.keys():
msg = 'Could not find the the target nuclide {0} in natural '\
@ -216,45 +228,49 @@ class Element(str):
.format(enrichment_target, self, list(abundances.keys()))
raise ValueError(msg)
# Check if is a single isotope mixture
if len(abundances) == 1:
msg = 'Element {0} consist of single isotope. Thus it cannot '\
'be enriched.'.format(self)
raise ValueError(msg)
# If weight percent enrichment is requested convert to mass fractions
if enrichment_type == 'wo':
# Convert the atomic abundances to weight fractions
# Compute the element atomic mass
element_am = 0.0
for nuclide in abundances.keys():
element_am += atomic_mass(nuclide) * abundances[nuclide]
# Convert the atomic abundances to weight fractions
# Compute the element atomic mass
element_am = 0.0
for nuclide in abundances.keys():
element_am += atomic_mass(nuclide) * abundances[nuclide]
# Convert Molar Fractions to mass fractions
for nuclide in abundances.keys():
abundances[nuclide] *= atomic_mass(nuclide) / element_am
# Convert the molar fractions to mass fractions
for nuclide in abundances.keys():
abundances[nuclide] *= atomic_mass(nuclide) / element_am
# Normalise to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Normalize the mass fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Enrich the mixture
# The procedure is more generic that it needs to be. It allows
# to enrich mixtures of more then 2 isotopes, keeping the rations
# of non-enriched nuclides the same as in natural composition
# Get fraction of non-enriched isotopes in nat. composition
non_enriched = 1.0 - abundances[enrichment_target]
tail_fraction = 1.0 - enrichment / 100.0
# Enrich the mixture
# Enrich all nuclides
# Do bogus operation for enrichment target but overwrite immediatly
# to avoid if statement in the loop
for nuclide, fraction in abundances.items():
abundances[nuclide] = tail_fraction * fraction / non_enriched
abundances[enrichment_target] = enrichment / 100.0
# Convert back to atomic fractions
# Convert the mass fractions to mole fractions
for nuclide in abundances.keys():
abundances[nuclide] /= atomic_mass(nuclide)
# Convert back to atomic fractions if requested
if enrichment_type == 'wo':
# Convert the mass fractions to mole fractions
for nuclide in abundances.keys():
abundances[nuclide] /= atomic_mass(nuclide)
# Normalize the mole fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Normalize the mole fractions to one
sum_abundances = sum(abundances.values())
for nuclide in abundances.keys():
abundances[nuclide] /= sum_abundances
# Compute the ratio of the nuclide atomic masses to the element
# atomic mass